Implantable blood pumps used as mechanical circulatory support devices or “MCSDs” include a pumping mechanism to move blood from the heart out to the rest of the body. The pumping mechanism may be a centrifugal flow pump, such as the HVAD® Pump manufactured by HeartWare, Inc. in Miami Lakes, Fla., USA. The HVAD® Pump is further discussed in U.S. Pat. No. 8,512,013, the disclosure of which is hereby incorporated in its entirety. In operation, the blood pump draws blood from a source such as the right ventricle, left ventricle, right atrium, or left atrium of a patient's heart and impels the blood into an artery such as the patient's ascending aorta or peripheral artery.
In an exemplary HVAD® Pump, an impeller is positioned within a housing having an upstream inflow cannula and a downstream outlet. The impeller is configured to rotate along an axis defined by the rotor and to impel blood upstream from the inflow cannula downstream to the outlet. In such a configuration, the impeller pumps blood in a direction substantially perpendicular to the axis about which it rotates. Dual stators are included in the pump, one upstream of the impeller and one downstream from the impeller and are each configured to rotate the impeller to impel blood. Disposed between the impeller and each respective stator is a non-ferromagnetic ceramic disk that separates the respective stator from the impeller and provides a smooth surface to pump blood. However, owing to the small gap between each ceramic disk and the impeller, the risk of thrombus increases as a result of potential stagnation of blood proximate the ceramic disk. Furthermore, the presence of bacteria in the blood also increases the risk of thrombus or infection, which may require medications, such as antibiotics, for treatment.
In another configuration, the pumping mechanism may be a flow pump which supports various flow types, such as the MVAD® Pump, also manufactured by HeartWare, Inc. in Miami Lakes, Fla., USA. The MVAD® Pump is further discussed in U.S. Pat. Nos. 8,007,254 and 9,561,313 and U.S. patent application Ser. No. 15/475,432, filed Mar. 31, 2017, the disclosure of which is hereby incorporated in its entirety. Blood flowing within the MVAD® Pump, like other MCSDs, is also subject to thrombus and infection.